Adjustable ellipse compass



Jan, 17, 1950 H. R. lRxcK ADJUSTABLE ELLIPSE COMPASS Filed May 16, 1944 Patented Jan. 17, 1950 ADJUSTABLE ELLIPSE COIWPASS Haden R. Irick, Phoenix, Ariz.

Application May 16, 1944, Serial No. 535,785

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) 4 Claims.

The invention described herein, if patented., may be manufactured and used by or for the Goverment for governmental purposes without the payment to me of any royalty thereon, in accordance with the provisions of the act of April 30, 1928 (ch. 460, 45 Stat. L. 467) The invention relates to improvements in an adjustable ellipse compass, with which ellipses of any proportioned major and minor axis, limited only in the greater dimension by the size of the instrument, can be drawn; and the objects `of the improvements are: First-to provide a compact instrument in a single unit and of small enough size to be of practical use in drafting; second-to provide an instrument thatJ will scribe or draw a complete true ellipse in one simple operation; third-to afford facilities for adjusting the instrument so that any true ellipse with any determined length major and minor axis may be drawn; and fourth-to afford a simple method of placing the ellipse compass in position for use on a drawing.

One form of the invention is illustrated in the accompanying drawing in which Figure l is an isometric View of the entire instrument, Figure 2 is the top view or plan of the entire instrument, Figure 3 is the front view of the complete instrument, Figure 4 is a full section view of that part of the adjustable ellipse compass on the line 4 4, Figure 3, and Figure 5 is an enlarged detailed view of one of the adjustment pointer assemblies.

The main frame I, to which is hinged by rivets or bolts 'I a base 6, constitutes the framework of the instrument. This hinged action allows the working parts of the instrument to be tilted so that an inking pen of the LeRoy type, which is designed for use with mechanical lettering devices and is provided with a cylindrical reservoir which supplies ink to a concentric hollow pen but which forms no part of the invention, may be held by the lead chuck or pen clamp IB, also forming no part of the invention. When the working parts are tilted the pen can be kept free of a drawing while the instrument is being placed in position for use, or being withdrawn from a drawing after using. LeRoy type lettering pens are illustrated in the catalog of Keuffel and Esser Co., New York city, 38th edition, copyrighted 1936, on pages 28S, 289, and 290.

Threaded through a tab projection on one end of the base 6 is an adjustment bolt I9, Figures 2 and 4, which bears against a portion of main frame l below the center of hinge l, so that the amount of the forward tilt of the working part of the instrument is adjustable. This allows the pen clamp I0 to be raised or lowered to any desired position relative to a drawing where it will remain as the instrument is operated.

A hollow square rod 5, on which the carriage 8 slides, is rigidly attached at each end to the U-shaped main frame I, by screws, solder or welding.

Carriage 8, shown in Figures 3 and 4, is constructed so that it allows a hollow square rod 9 to slide transversely through it. Rod 9 lies at right angles to rod 5 so that there is provided a means of both transverse and longitudinal motion, each at right angles to the other and both Lin the same plane.

A slotted frame 3 shown in Figures l, 2 and 4, is attached rigidly to the ends of rod 9 and eX- tends above and over said rod so that enough clearance is allowed for free sliding of rod 9 through carriage 8.

Two slots 2I and 22 are cut in frame 3, one transversely and the other forming `a ninety degree angle with said transverse slot, intersecting at the center of the frame so that the slots are at right angles to each other and parallel to hollow square rods 5 and 9, respectively.

Attached to one outer extremity of said frame 3 is a clamp Ill for holding an inking pen or pencil lead chuck. The type of said clamp forms no part of the invention.

A threaded shaft, which is machined with a shoulder so that when knob 4 is tightened against a washer having a pointer 29 affixed thereto that rests on the shoulder, the shaft remains free to turn in a hole drilled for it in the main frame I directly over the center of rod 5, is anchored to a calibrated scale 2 shown in Figures l and 2.

The scale 2 is calibrated in inches and fractions thereof, beginning at its center of rotation as zero and progressing outward along a slot cut in the scale to the end of said slot. One-fourth inch of said calibrations shall be designated as l/z, and one-half inch shall be 1, etc.

Two identical slide guides I5, Figure 5, are

machined to a sliding fit for the slots 2l and 22 in frame 3 and are placed, one in the transverse slot 22 and one in the longitudinal slot 2l of said frame, with two identical bolts IE extending through them. Said bolts are machined with a shoulder which extends through said slide guide and against which a washer I 4 is placed. The bolts then extend through the slot in calibrated scale 2 and two pointers I2 and I 8 are placed thereon bearing directly on the surface of said calibrated scale. Two spring washers I3 are then placed on the bolts and the tension nuts Il and I1 are screwed on. It can readily be seen that the tension exerted by said nuts will be transmitted through the spring washers and the pointers to the calibrated scale 2 between the washer ld and the pointer, leaving the slide guides free to rotate on the bolts. The pointers I2 and i8 will remain in any set position on the calibrated scale 2.

The adjustment pointer I2 controls the major axis and adjustment pointer |18 controls the minor axis when an ellipse is drawn.

It can readily be seen that if knob 4 is turned, calibrated scale 2 will rotate, causing the slide guides l5 in the slots 2|, 22 of frame 3 to slide in the direction of rotation and, in turn, causing frame 3 to follow the transverse and lateral motions supplied by the arrangement of carriage 8 and the square rods 9 and 5, thus converting the two circular motions supplied by said scale 2 and its adjustable pointers into a single motion, resulting in the pen clamp l describing a perfect ellipse as one complete revolution o knob i is made.

I am aware that, prior to my invention, drafting instruments for drawing ellipses have been made, and I have shown and described one embodiment of my invention, but it is to be understood that it is capable of many modications. Changes in the construction and arrangement may therefore be made Without departing from the spirit and scope of the invention as disclosed in the appended claims.

What I claim is:

1. In an ellipsograph provided with a longitudinally slotted bar bearing graduations transverse to said slot, a cross-shaped frame having intersecting longitudinal slots, a marking instrument holding means rigidly connected to said frame and two slide guides adapted to be adjustably secured to said slotted bar and to slide in the slot-s of said frame, the improvement which comprises a supporting base adapted to rest on a plane surface, a main frame hingedly supported by said base whereby rocking the cross-shaped frame lifts a marking instrument, a guide bar secured in said hinged frame, a sliding carriage mounted on said guide bar provided with a means for slidably mounting said cross-shaped frame, and a pivot in said main frame and said slotted bar with an operating knob for manually rotating said slotted bar.

2. An ellipsograph according to claim 1 wherein each of the two slide guides is provided with a pointer for aiding in accurately adjusting said guides with respect to each other in said bar and resilient means for holding said slide guides in position along said slotted bar.

3. In an ellipsograph provided with a frame having a cross-shaped slot, a slotted bar provided with terminal pivoting means and graduations transverse to the slot in said slotted bar, two slide guides each adapted to be adjustably secured in said slotted bar and provided with extensions which slide in said cross-shaped slot, the improvement which comprises a supporting base adapted to rest on a plane surface, a main frame hingedly supported by said base and also providing the pivotal support for said bar beneath said frame, a guide bar rigidly secured to said hinged frame and forming therewith a closed loop, a sliding carriage mounted on said guide bar provided with means for supporting said slotted frame, which supporting means permits said frame to be moved transversely of said guide bar, and means for manually rotating said slotted bar and thereby moving a suitable drawing instrument guided by said slotted frame.

4. In an ellipsograph provided with a crossshaped frame each arm of which is slotted, a pivoted slotted arm provided with calibrations, two slide guides mounted in the slot of said arm, a bolt for each guide which extends into a slot of said Ycross-shaped frame, a pointer for each slide guide for aligning said guide with a selected scale marking and means carried by said frame for holding a marking instrument, the improvement which comprises a main frame, a base to which said main frame is pivotally connected whereby rocking the cross-shaped frame lifts the marking instrument, means for pivotally connecting said slotted arm to said main frame including an operating knob, a non-circular rod united to said main frame, a carriage provided with a sleeve for said non-circular rod, and also provided with a non-circular sleeve offset from said rst sleeve and perpendicular thereto, and a non-circular rod slidable within said second sleeve and terminally rigidly connected to said slotted frame.

HADEN R. IRICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 296,100 Abbott Apr. 1, 1884 492,142 Corkhill Feb. 21, 1893 910,129 Hanson Jan. 19, 1909 973,047 Jeter Oct. 18, 1910 1,168,081 Kirk et al. Jan. 11, 1916 FOREIGN PATENTS Number Country Date 144,157 Great Britain June 10, 1920 

